Barry Allen comes to Starling City in Wednesday night’s Arrow, but one thing viewers will quickly learn after meeting the young, eventual superhero? Oliver Queen Jr. he is not.

“He’s sort of the opposite of Oliver in a lot of ways,” executive producer Andrew Kreisberg told reporters at a screening held this week. “Barry’s outgoing and funny and a little bit unsure of himself and smart and sort of a squeaky wheel. And the contrast between Stephen and Grant is comical and fun and has been great to watch.”

Grant Gustin, who was cast back in September after an extensive search, says Barry’s uniqueness immediately drew him to the part. ”I immediately thought he was endearing and funny, and I hadn’t done anything like that,” says the actor, who previously was best known for playing not-so-good guy Sebastian Smythe on Fox’s Glee. ”He’s fun to play. He’s likable. I would be his friend. And I haven’t had the opportunity to play a character I would enjoy spending time with.”

Allen, meanwhile, spends quite a bit of quality time with Felicity Smoak (Emily Bett Rickards). Gustin’s chemistry with Rickards, says Kreisberg, was something they tested prior to deciding which actor would grab the role of Barry Allen. And while he acknowledges fans’ love of so-called Olicity, he says, “It just seemed like [Felicity and Barry] would instantly hit it off, which would just complicate things for Oliver even more, and it just seemed like the right way to go.”

Wednesday night’s episode will mark the first of two planned appearances on the show. There had previously been plans for him to appear once again in the 20th episode of Arrow in 2014, but those plans were scrapped when producers decided to nix the idea of a backdoor pilot, opting instead to do a standalone pilot. “In some ways making that the backdoor pilot made things a little harder because we had to make a right turn from our ongoing story to incorporate that. In some ways, this has freed us to take the Flash and just do the Flash separately,” said Kreisberg. DC Comics’ Geoff Johns added that much of the mythology and character from the comics will be used in the development of the show. “I don’t want to get too specific yet, but you’ll see a lot of characters and a lot of elements form that.” But the big question? Will any characters from Arrow appear in the Flash pilot? “Definitely there’s a chance,” says executive producer Greg Berlanti.